The present invention has for its object a device for the introduction and/or the removal, in an airtight manner, of solid bodies across at least one aperature of an enclosure treatment, more particularly under low pressure.
The object of the invention pertains more particularly fluid dynamics.
Many up to date surface treatments are carried out within enclosures in which a more or less substantial vacuum is provided. There are such treatments which are carried out with a vacuum in the order of 1,333. Pascal, for instance the treatments in the vapour stage, or in the order of 1,333.10.sup.-1 Pascal, this is for instance the case of the deposits of titanium nitride through spraying.
At the present time, the machines for vacuum treatment are discontinuous. In a general manner, they have a series of chambers in which different vacuum heads may prevail, said chambers being adapted for scouring, treating, drying, cooling, etc. in succession. Each successive step is characterized by the simultaneous opening of a plurality of valves which separate the enclosures two by two, and by the advancement of the whole of the treatment line, equal to the modular length of one enclosure. After each valve closing, the vacuum pump assemblies are actuated in order to restore the desired pressure.
Such systems are not suitably adapted for treating products of substantial length or continuous, solid products, such as wires or sheet metals. When the solid body is travelling between two consecutive enclosures, as the pressure differences on either side of the wall are rather small, it is possible to do with a single aperture of communication, the discharge of the pumps compensating the leakage from an enclosure to the other one. However, the problem is different when the solid body is to be passed from the outside into the first enclosure, or from the last enclosure towards the outside. In this case, the well-known conventional systems are all of them burdened with defects, the more often latent ones.
This is more particularly the case with the following treatment procedures:
When as small clearance as possible is desired between the wire, or the sheet metal, and the outlet aperture, there is a scraping of the product against the wall. Although the resulting marks or scratching could sometimes be tolerated, prior to the treatment of the product, they occur again after the treatment, when the product is leaving the apparatus.
When it is desired to cause a friction of the product, either a product of some length or a continuous product, within the interior of an elastic sphincter, there are then further drawbacks to be encountered as soon as the pressures are falling below some tens torrs, among which: degassing of the product, saturating vapour tension, exposure to heat or cold, pollution of the surface of the treated product, etc.
When it is desired to have the product passed through a duct with a clearance of sufficient width to prevent the contact, and when various offset portions are provided, each one with suction means, it is then necessary to arrange a power rating in excess. Moreover, in the case of a continuous product, which is broken inadvertently, the automatic re-threading of said product without stopping the line is elaborate and rather uneasy.
The obtention of a sealing, or at least of a sealing in part, by means of ferrofluids has also been suggested. However, there is here to be encountered either the saturating vapour tension of the liquid part of the ferrofluid, or the magnetism of the product; for instance, it is not possible to obtain a sealing with ferrofluids subjected to a magnetic field when the is on a basis of iron.
In accordance with the invention, and to overcome these disadvantages, a device has been provided in a particularly simple and efficient manner, which permits the introduction and/or the removal, in a substantially airtight manner, of solid bodies across at least one aperture of a treatment enclosure the internal pressure of which is lower than the pressure in the immediate surroundings.